


After-Action Report

by ArcherUmi



Series: Kinktober 2020 [9]
Category: Girls und Panzer
Genre: Caught, Cunnilingus, F/F, Kinktober, Kinktober 2020, Mentioned Itsumi Erika/Nishizumi Maho, Polyamory, Sibling Incest, Threesome - F/F/F, Vaginal Fingering
Language: English
Status: Completed
Published: 2020-10-29
Updated: 2020-10-29
Packaged: 2021-03-08 19:07:50
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,319
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27261733
Author URL: https://archiveofourown.org/users/ArcherUmi/pseuds/ArcherUmi
Summary: There is one entry in Itsumi Erika's diary that, even more than the others, is confidential.Prompt: Incest
Relationships: Itsumi Erika/Nishizumi Maho/Nishizumi Miho, Nishizumi Maho/Nishizumi Miho
Series: Kinktober 2020 [9]
Series URL: https://archiveofourown.org/series/1950772
Kudos: 12





	After-Action Report

**Author's Note:**

> Like a lot of my Kinktober fics, this started as an idea I had a while ago and Kinktober seemed like a good opportunity to actually use it. Incest fics are a big guilty pleasure for me honestly so I knew this was one of the kinks I wanted to include since I haven't written it myself in a while, and I actually had a few different ideas before I came back to this one. It's been a while since I watched Girls und Panzer but I did enjoy it (after giving it a second chance when some friends did a group watch; the first time I watched it I actually hated because of how unlikable the student council is before you know their motivation and how desperate they are), so it was fun to get back to it.
> 
> I didn't love Erika when I watched the series (although I didn't hate her which I think all of my friends did), but a lot of the time writing a character makes me appreciate them more, and writing this – and even more so reading a bit of her spinoff manga, _Phase Erika_ – definitely made me like her more. I don't think I really shipped anyone very much either, besides thinking Miho and Maho were cute together in fanart and doujins and maybe Miho/Yukari when I first watched it, but now I think I'm actually feeling the Miho/Maho/Erika OT3 too.
> 
> As the summary suggests, this is a bit different in that I tried to write it in the first person in the style of a diary entry, which I was a bit apprehensive about since I've heard that first person is not very popular in fanfic. I'm not sure how well I did or how well I captured Erika (I do _think_ I have her down ok and same with Miho while Maho is the character I least felt I had a good read on, but I feel like getting the character right is probably especially important in a fic from this kind perspective), but it was fun to write something like this and to try and be her for a few thousand words.

... Having already taken punishing losses at this point, Viggen High's final gambit was to break for the valley under smoke cover, evidently taking a page from Ooarai's strategy at the National finals that caused some trouble for us. As we had already climbed the hillside, the Commander ordered my detachment to the valley rim first and began ascending it herself with the main part of our force. However on reaching the valley I saw no sign of Viggen High's tanks and quickly deduced that they had executed a feint.

I communicated this to the Commander, who turned back, charged down the hill, and was able to cut off Viggen's remaining force before they flanked us through the forest to the east and quickly immobilize their flag tank. It was unfortunate that I didn't have much opportunity to get any action myself during the match, but as I expected from the beginning it was a Kuromorimine victory.

My assessment in three parts. First, while Viggen High School is definitely a third-tier team, I will give them credit for fighting with respectable sportsmanship and losing honorably. Second, while the Strv m/40 is highly inadequate as I expected from the records I could find of its use in war service by Hungary, the Strv m/42 though certainly not a match for our Tigers performed well.

Third, as a team we're getting better at responding to unexpected situations and eccentric tactics. Even if this was only a friendly with a third-tier team, I expect now that we've notched our first win since the stinging Nationals loss and since the Commander instituted our new training regimen the public will finally be convinced that claims of the end of the dominance of the Nishizumi Style over _Sensha-dō_ have been blown completely and utterly out of proportion.

Following the match briefly returned to the hotel to shower and change out of our combat uniforms before dinner. As no suitable German restaurant could be located in Niigata, with the team's input the Commander selected one specializing in Niigata-style _tare-katsudon_ which thankfully could accommodate such a large party. Miho, who had taken the train in from Ibaraki to watch the match, also attended. Food was good though I would have appreciated slightly larger portions after spending most of the day in the field.

After dinner I intended to speak to the Commander in more detail about our performance and our strategies going forward, however she had already left while I was using the restroom. I inquired about her and was told by Maaru-san that the Commander had left with her sister and returned to her hotel room to catch up, and that she had asked not to be disturbed. I told Maaru-san that I was sure the Commander wouldn't mind my intrusion and left early as well.

I've made clear the issues I have had in the past with Miho. However, I greatly respect the Commander and her relationship with her sister is none of my business, and despite what some have claimed I am not incapable of being courteous.

I also have been clear about my own private liaisons with the Commander and the rules of engagement thereof that stood until tonight – that I accept however begrudgingly that she is not interested in an exclusive romantic relationship with me as she is already in a 'complicated' long-distance relationship, but that she has permission from her girlfriend to sleep around when they aren't together. Like the idiot I am, I accepted this from the beginning even though I knew it would hurt me because it was the only chance I had with Maho.

I confess though, I'm surprised where it's ended up. It might turn out better than I thought it would.

Anyway. Arrived at the hotel, and after going to her floor knocked on the door to her suite. There was no answer even after knocking twice, so I decided to try the knob and see if the room was unlocked, which it was.

On entering the suite, I was shocked to see the Commander on a dining chair with her sister sitting in her lap – more accurately Miho was straddling her – the two of them in a state of partial undress and sharing a decidedly un-sisterly embrace.

Both of them noticed, obviously, and turned to look at me with concerned expressions – Miho's close to fearful – before addressing me. Miho spoke first.

"...I-Itsumi-san?".

"Erika... I...", Maho said, before adding "...Close the door."

I was still standing there, gaping at them and trying to collect my thoughts. The sensible thing to do would have been to simply close the door, go away, and forget I had ever seen what was behind it, but I at that point, absent of mind, decided to instead close it behind me and leave the three of us together in the room.

Miho glanced back at the Commander, saying, "Sorry, Onee-chan... I forgot to lock it."

Now that I'd had time to process the situation, of course, my feeling was one of distaste, though I was less disgusted than I would have expected. I assume it would have been about the same for any normal person – certainly I can say I've never had sexual thoughts about my own older sister in my life. I don't know if I had the right to be upset – I had a clear understanding that the Commander's romantic life outside of me was none of my business and neither was her sibling relationship – but I can't say I wasn't or that it was unreasonable of me.

"Is... Is this really what's going on here, Commander?", I said. I'm sure it came across that I felt hurt. Maho was frozen, and in hindsight as someone who has a hard time showing her feelings I'm also sure she was having a hard time processing what to do. Having given her a chance to respond though, I continued, and I will admit what I said may have been out of line – "Maybe it's none of my business, but I hope you at least have enough respect for me to say something for yourself."

The Commander nodded and motioned for Miho to get off of her. She stood up, re-buttoned her uniform shirt, and even tucked it in to her skirt before she spoke, and I was surprised to see her bow in apology to me, her underclassman and subordinate.

"I'm sorry... I wasn't able to tell you or anyone, and I know they are wrong, but yes, these are the feelings I have for Miho."

You would expect some people caught like this to deny or make excuses, but such is the honor of the Nishizumi School. There is a very good reason for the respect I have for Commander Nishizumi Maho.

Self-consciously, her sister stood up straight as well and then bowed with her. At this point I really didn't know what to do. Do I accept their apology? Am I the one they need to apologize to? Luckily the Commander gave me an out, politely asking me to leave before turning to Miho and telling her it was probably for the best that she left as well.

What I did not expect in the least was for Miho to disagree, before saying, "If Itsumi-san saw already... It would be fine for her to stay if she wanted to, isn't it?".

"...Miho?", the Commander asked.

"Onee-chan, um... You said before you slept with Itsumi-san, right?", Miho said. I could tell how nervous she was. "I love you, Onee-chan, and I'm glad you feel the same, and that you want to stay with me, but... I don't know it's fair how you've treated her when she loves you that much too, you know?".

Her talking about me almost like I wasn’t there – not to mention her casually diagnosing _and_ telling the Commander my true feelings – was getting on my nerves, even if she was standing up for me.

"So I've been thinking", she continued, "It would be ok for her to join us". Miho then turned to me – she had only been getting more and more nervous as she went on – and added. "Um... I know we've never gotten along, but... I-I don't hate you for it Itsumi-san, really."

First of all, why the _Scheiße_ is she so nice? To me? Weird to say but it kind of pisses me off. Second, after again taking the time to process it, her offer floored me.

By this point I had gone from dazed to hurt to morbidly intrigued with the sheer transgressiveness of it. I'm still a tiny bit disgusted with myself that at that point part of me kind of _wanted_ to see the Commander fuck her sister, and I should probably be a lot more disgusted than I am. And when it comes to Maho, sometimes my rational brain does not make decisions for me. So, a ridiculous offer like that was...

The Commander meekly protested, "Umm, Miho... That's...".

Suddenly stricken by nerves as well I thought about declining or postponing before stuttering out, and I wish I at least could have maintained my confidence instead of turning into such a wreck in front of the Commander and Miho, "Errm... Well, if you were going to invite me, I would... So."

Maho paused before smiling. That warm look isn't too common to see, so it's one of the most precious things in the world to me. "Hmm. I see. Well, if neither of you are opposed it's fine, isn't it?".

"...Do you want to pick back up where we left off then, Onee-chan?", Miho asked sweetly. If I'm being honest, she's cute herself, even her sometimes annoying mannerisms, though she's not as beautiful as the Commander.

"With Erika watching is fine, Miho?".

"I'd, erm, be fine with watching for a bit", I said, mentally kicking myself after I realized the Commander had certainly been concerned more about _being_ watched than about me. My heart rate must have been higher than during any _Sensha-dō_ match I've fought in, even the two National finals.

Miho laughed, saying, "Yeah, it's fine."

Remembering my own intrusion, I locked the door. The following unnecessary details are for my own personal future reference.

The Commander sat down again, unbuttoning her shirt, as I stood against the door. Maho shot me a glance as she pulled it open, and from the expression and stifled giggle she gave me before turning her head back I probably looked like a lovestruck fool the moment she did, which I probably have most of the times we've had sex too. I had to look away in embarrassment myself, if only for a second.

Miho had removed her skirt – she had already taken off her shirt before I came in – and returned to her sister's lap as I looked back. Without a hint of shame she planted a kiss on the Commander's lips.

It was still hard to process what I was seeing. The Commander threw her arms around Miho's back as they kissed, and they even broke away for air before going at it again. From the way they embraced and kissed, I could certainly tell how genuine their love for each other was.

The Commander reached down below Miho's shoulders and undid the clasp of her bra, pulling it off and dropping it on the table next to her, then slipped her arms out of her shirt and let it slump down off her shoulders as she leaned forward and allowed Miho to do the same for her. The Commander was the one to initiate the kiss this time. I confess I felt a pang of jealousy seeing her push her bared breasts against Miho's and worm her hand into her lap beneath her underwear, tempered by knowing I'd get my turn soon enough.

I shoved my own hand into my lap under my clothes when I saw that – it was embarrassing how wet I had gotten watching them. I'm praising her too much tonight, but Miho makes cute moans when she's getting fingered. Or eaten out.

"...Want to move somewhere more comfortable, Onee-chan?", Miho said after a few moments of the Commander's hand in her panties. She looked straight at me, my hand down my skirt – not that this hadn't already gone far enough that there wasn't really room left for shame, adding, "Eririn seems lonely, too."

I'll really never forgive her for coining that nickname for me. I only called her 'Miporin' _one time_ and I didn't even mean to!

I returned fire, snarling back, "Shut up, Miho!", before reluctantly – hoping at least that it would stop her from calling me 'Eririn' – adding, "...You can just call me Erika if you like."

Again stifling laughter, the Commander replied, "Sure" to Miho. Miho got off of her, and me and the Commander both followed her toward the couch as she slipped off her panties and dropped them on the carpet. The Commander undressed as well, and sat on the couch watching as I followed suit and left my school uniform and then my underwear on the coffee table.

Taking a seat on the opposite end of the couch myself, Miho sat in the Commander's lap, her back pressed against her chest, and Maho started kissing her neck and fondling her breast while her other hand went to Miho's lap again. She watched as I resumed touching myself as well, before her eyes glanced back to her lap where Maho's fingers were pressed to her cunt.

With a giggle, Miho said " _Panzer vor_ ", and sighed as the Commander slipped them in to her. I watched intently, pumping my fingers as the Commander's did the same to Miho and listening as she softly moaned 'Onee-chan' and to wet sounds coming from her lap. Miho again glanced over to me, and Maho seemed to take notice, smiling again.

"You want to switch to a different formation, Miho?".

She giggled. "Mhm... Even if you were fine watching Its--", she stopped herself, "--Erika... It would be better if all three of us could at the same time, right?".

'Itsumi-san' would be better, but as long as it's not 'Eririn'. I was enjoying the show enough to not mind waiting, but obviously I wasn't going to complain.

"No objections", I said. I decided to play along, looking to Maho. "Your orders, Commander?".

"How about you lie down, Erika?", she said, letting out a tiny giggle herself as she took her fingers out of Miho and let her stand up.

She stood up as well and I followed her command, lying down on the couch as she instructed Miho to one end of it before straddling my face, kneeling over me and facing her sister. The Commander lowered her hips, I felt Miho's fingers brush against me, and, despite my view being obstructed as I stuck out my tongue and tasted Maho before grasping her hips and beginning to eat her out in earnest, I noticed both of them lean towards each other. Even with Maho dripping on my tongue as I licked her and Miho's fingers rubbing my clit and dipping into my cunt to occupy me, it was hard for my thoughts not to stray to how _Gott im Himmel_ the Commander and her _sister_ were on top of me frenching each other. I'm not sure how I'm going to be able to face my sister next time I see her after how much I enjoyed that, but I confess it turned me on.

What's gotten in to me? Forgive me, Onee-chan.

It didn't take very long for Miho to make me come – partly because I was already sensitive from watching her and the Commander and playing with myself, but being with Maho has certainly taught her well. I was still moaning into her lap and feeling myself contract around Miho's fingers when I put the Commander over the edge a moment later and heard her practically shout into her sister's mouth. She got off of me and kissed my lips as I sat up, and it occurred to me as we made out that with how much she had been kissing Miho, I was probably tasting her on Maho's lips too.

I got one more surprise as Miho crawled over and sat in my lap to make room for the Commander.

"Onee-chan... Want to lick me?", she said, and Maho pulled away from our kiss. "You didn't get off yet, huh, Miho?".

She shook her head, and the Commander smiled and knelt back on the couch, dipping hers between Miho's legs and grabbing her hips as she buried her face in her lap and stuck out her tongue. I could feel Miho shiver and she ran her fingers through the Commander's hair, her moans – 'Onee-chan, mmm, don't stop, Onee-chan' – getting steadily louder as I watched Maho quickly bring her sister to her climax as well.

We talked a bit as we got dressed again, me after washing my face and using some mouthwash, and afterwards, a little bit about how this will work if we make it an ongoing thing and not a one-off but mainly reminiscing about our time at Kuromorimine together and some arguing about the National finals match. Luckily I stopped myself before I got too worked up about them. Those are still memories that sting a little.

All three of us had skipped dessert by leaving the restaurant early, so at Miho's suggestion we found a place near the hotel and ordered parfaits, which I guess counts as our first date of sorts. Miho ordered strawberry while both me and Maho chose chocolate, and she casually offered me a taste and then gave one to me – off her own spoon! – when I said yes. I gave her a taste of mine in return of course, although I told her to use her spoon and she gently ribbed me about how grumpy I looked about it.

She went to do the same for the Commander, but stopped herself. The whole meal was all a little surreal, and in that moment I felt bad for them too. As recognizable as they are from _Sensha-dō_ , a relationship like theirs is much too dangerous to exist in public, even in an unfamiliar city. It's oddly exciting then that I get to see it.

Afterwards, me and the Commander returned to the hotel, while Miho left us to catch her late train to Tokyo and rejoin Ooarai's school ship at Yokosuka tomorrow morning. Never got around to the strategy discussions. On returning to my room, I immediately had to write these words. This is an unusually long entry for me but it's been a long, strange day and I wanted to write down my recollections while they were still fresh in my mind.

Even if she still frustrates me sometimes need to work on my relationship with Miho. We're girlfriends too now, right? Is that how this works? It's confusing. I will stand by my belief that nothing I've said to her has been entirely unjustified, but I have never been especially kind to her, and despite what she says I'm not sure how she feels about this new arrangement. I don't want to feel like I'm just waltzing in and stealing her sister – sister _and_ girlfriend – from her, even if it got me what I wanted.

Come to think of it, I don't want to do the same to the Commander either. She's always been fiercely protective of her younger sister, too. Maybe I'm overreacting but I feel like I'm going to ruin their relationship and my entire _verdammt_ life if I screw this up.

Still... Sharing both Nishizumi sisters with each other isn't too much of a price for having a deeper relationship at last with Maho. After tonight, I'm not sure it's even a price to me at all.

**Author's Note:**

> I feel like this probably takes things too quick – I've always struggled a bit with the transition from setup to smut – and it definitely feels more like hentai than anything I've written in ages. Maho confessing to being in love with her sister and then Erika going from being hurt and weirded out to being in to the incest seems way too fast, but it was already getting longer than I intended and I didn't set out to write a semi-realistic dramatic story about an incestuous relationship (although maybe I should have).
> 
> I don't really trust the Girls und Panzer wiki very much given some of the strange seeming information on it (like the theory that the American-themed school being based in Nagasaki Prefecture is a reference to the atomic bombing, which... Well, maybe, but their home port of Sasebo is a major base for the U.S. Navy and that always seemed like what the reference was to me), so I was skeptical of it claiming Miho nicknamed Erika "Eririn". I looked it up, couldn't find anything at first, and almost considered asking my sister about it because I think she read _Little Army_ , but I tried again while I was finishing this up and found the 4-koma that as far as I know it comes from and just had to slip it in.
> 
> I've never really felt comfortable using the word "cunt" even in smut – I always thought of it as about the "worst" word there was outside of, like, hard slurs – but even if Erika's arrogance and harshness is partly a front I kind of felt like using it suited her.


End file.
